Sunday, September 21, 2014

The Bougie Review Part I: By the Numbers

First let me say thank you to everyone on Twitter or Facebook or carrier pigeon who heard about the Bougie survey, filled it out and shared it with others.  Only by the goodness of people like you, and a little help from technology, was I able to collect so much information in such a short period of time.

As I said before, the review of bougie usage for intubation is being released in two parts. This article deals strictly with a breakdown of the numbers collected from the survey, which mainly dealt with attitudes, training and experience using the bougie. Part two will be a more extensive literature review that will most likely reference these numbers and relate them to the broader evidence for and against using the bougie in clinical practice. 

The Survey
Using Survey Monkey (www.surveymonkey.com), I constructed a very simple 10 question survey using the questions and answer choices below:
1.       Have you received formal education on how to use a bougie to facilitate intubation?
Yes/No
2.       Have you used/trained with a bougie on an airway manikin?
Yes/No
3.       Please rate your level of comfort in using a bougie to facilitate endotracheal intubation on a live patient.
Very Comfortable/More Comfortable/Neutral/More Uncomfortable/Very Uncomfortable
4.       Have you ever used a bougie to facilitate a live intubation, and if so was it successful?
Yes, successful/Yes, unsuccessful/No, I have never used a bougie for a live intubation
5.       If you have used a bougie to facilitate intubation, did you use it:
Two-person railroad technique (place the bougie, then have an assistant guide the tube onto the bougie
Pre-loaded into tube, similar to technique used with malleable stylet.
I have used both of these techniques
I have never used a bougie on a live patient
6.       When performing orotracheal intubation on the first attempt, what device do you prefer to shape and guide the ET tube?
Malleable stylet/Bougie/No device/Something else
7.       Would you find more airway education, especially related to using the bougie, useful to your practice and professional development?
Yes/No
8.       Please rate your level of comfort in performing endotracheal intubation on a live patient
Very Comfortable/More Comfortable/Comfortable/More Uncomfortable/Very Uncomfortable
9.       Please select your credential under which you practice intubation:
Physician/CRNA/Anesthesia Assistant/Nurse Practitioner/Physician Assistant/RN/Paramedic/Other
10.   How many years have you been performing live intubations under any credential?
0-1/1-3/3-5/5-10/More than 10

As you can see, this is a pretty blunt little tool, and not at all meant to divine scientific data about usage or success rates with and without the bougie. Rather, my hope here was to develop some ideas about current attitudes to help guide the current article and shape further research. 
Some of the admitted weaknesses with the survey are:

·         It asks about years of intubation experience, not how many intubations.  A physician in a busy, urban ED could intubate hundreds of patients during his residency and many more in his first couple of years as an attending. Conversely, a less taxing stint in a small community ED may see 10-20 intubations per year. The same can be said for practice environments across all the credentials collected here.
·         Speaking of practice environments, there was no question about that either.  Not specifying “EMS” or “Air Medical” or “Acute Care” led almost 9.5% of respondents to select “Other” for their credential and specify that they were flight/CCT paramedics or nurses.  Asking this question could very likely have provided another way to sort the data.
·         One question asked if the clinician had ever used a bougie, and if so whether or not it was successful.  This is valuable, but not as valuable as knowing how many intubations had been tried with the bougie, and how many of the total attempts had been fruitful.  Of 322 respondents that have used a bougie clinically, only five people responded that their bougie experience had been unsuccessful.  I suspect two things about this: 1) Those five people have never had a successful experience, as they probably would have reported their best result, and 2) The remaining 317 people probably had some failures, but the structure of the questions led them to report that they had been successful at least once. Or, more optimistically, that they had succeeded more often than they failed.
·         The question about how they used the bougie (railroad, preloaded or both) should have asked their preference.  I make a small leap in the analysis that this was the respondent’s intent, but that supposition is not supported by science.

The survey was distributed via the web, primarily on social media groups populated mostly with critical care transport clinicians, acute care practitioners and prehospital EMS personnel.  Responses came from all over the world, most commonly the USA, Australia and Europe.

The Respondents

A total of 380 clinicians responded to the survey, and they were further separated for study by credential and years of experience.
 


 








For simplicity’s sake, clinicians that identified as “other” and listed a credential that contained “nurse” or “paramedic” were classified as one of those things.  If they self-identified as both, I classified them as whichever one they listed first. No one identified as an anesthesia assistant or physician assistant, so they are not included.  The only “Other” responses that were completely unique were respiratory therapist (there were several varieties of RT that got simplified) and one student nurse anesthetist.  Years of experience required no adjustment though it may have been useful to break the largest group, “More than 10 years” down a little further since it made up nearly half of the sample population.  The survey specifically asked how many years under any credential and not the current one since many providers begin their careers in one discipline and move either laterally or upward in terms of licensure and practice environment. 

Training: Past and Future
Not surprisingly, nearly everyone (98.7%) who responded has had some sort of training in using the bougie, either a formal education session, manikin practice or both.  That translated across all credentials and experience levels with the lowest incidence of training occurring in paramedics and those providers with less than one year of experience, though neither of these reached statistical significance.  Training, success and comfort level appear to be linked, at least negatively, as three of the five respondents who have had no training, have never tried to use the bougie and feel very uncomfortable about the prospect of doing so.  The other two without formal training reported they had been successful at least once and they were at least comfortable with using the bougie.  I can only imagine how confident I might be with something at which I had succeeded without ever being trained. 

What is a little quizzical is how many providers don’t believe that further training with the bougie would be beneficial to their practice or professional development (24.4%).  As you can see, the numbers are distributed fairly evenly across the years of experience with predictably fewer respondents in favor of more training as experience levels rise.


 Looking at credentials makes it a little less clear. Slightly more than half the physicians don’t want more educations, which may not be unusual given the length of initial medical education. The largest number of providers who want more training is the paramedics, while nurses come in about the same as the overall average. Of all the clinicians who did not want more training, 31% prefer using the bougie on a first attempt, and all but one of those have at least three years of experience, perhaps indicating a self-perceived level of competence among this group in using their tool of choice. I found it a little distressing and somewhat hard to believe that anyone who intubates, or performs any invasive skill for a living for that matter, would not find value in at least some ongoing education and training. 

One response made me wonder if I should have asked the question “Have you ever heard of a bougie before?” A physician with less than one year of experience reported that he had no formal bougie education, had never used one, was uncomfortable with using one and didn't want any education about using one.  I had to wonder if the word Bougie means something else, and something bad, where he is from.

Success and Failure
This is the part you were waiting for, right?  Of the 380 respondents, 322 stated that they had used the bougie on a live patient and 317 of those responded that they had been successful.  As stated above, I believe there are probably some failures hidden in that number, but the question was not sufficiently powered to find them and providers, rightly so, answered with their best performance.  Training and comfort level with the bougie and with intubation overall appear to be linked to success. The numbers lead me to conclude that training is inextricably linked to success (quick, call the Nobel Foundation). It is well documented that muscle memory, identification of landmarks and manipulation skills are enhanced by experience and reinforced by successes (1).
 
There were only five failures reported and again I surmise that those clinicians have never had a success when using the bougie or that’s the experience they would have reported. The table below lists the details of each respondent who reported an unsuccessful bougie experience:




 As you can see, the clinicians that reported failure were all educated, very experienced and comfortable with both intubation and bougie usage.  One possible explanation for this lives within the nature of airways themselves.  Several sources report the true incidence of difficult airway, depending on definition, at between 3%-11% of all cases (2).  Further classification of truly bad airways that cannot be rescued by means other than surgical, referred to as “Cannot intubate, cannot ventilate” (CICV) can be found in 0.01-0.03% of cases(3).  The failure rate reported in the survey is 1.5%, higher than the incidence of CICV but below average of reported airway difficulty. Thus I contend it is very plausible that the airways encountered by these trained, experienced providers were difficult, maybe impossible airways for which there was little hope short of a scalpel.

See One, Do One, Teach One, BE ONE!
Most of the clinicians who have used the bougie are comfortable with both its use (95%) and intubation in general (97.89%).  Only five people reported being uncomfortable with both, even though four of those claimed a successful bougie experience. To their credit, all five would find more education beneficial.
These findings seem to suggest that using the bougie improves the comfort level, or at least that an elevated comfort level from adequate training increases the likelihood that a provider will use the bougie. But with training levels, successful use and confidence levels all being above 95%, discerning which has the most positive effect is beyond the reach of the survey.

Choices
The survey looked at two different preferences: what providers choose to shape the tube on first attempt and what technique they used when they employed the bougie. One the first question, a majority of providers across all credentials surveyed prefer a malleable stylet over a bougie on their first attempt. This wasn't especially surprising since, even though the bougie was first introduced in 1949(4), its widespread use in acute care, transport and prehospital medicine has peaked only in the last ten years.  The same preference is true across all measured experience levels.  Paramedics had the greatest affinity for the bougie on first attempt (42.97%) among the credential groups and the 3-5 year experience group had the greatest bougie preference (44%). It is worth noting that an overwhelming majority of that group is made up of paramedics.

Summary
The survey, though not very powerful, did seem to affirm some widely held beliefs. Training in use of the bougie is widespread across all credentials and experience levels.  Though it would have been beneficial to know where the providers practice intubation, the primary distribution of the survey link suggest that it was mostly completed by clinicians involved in air/ground critical care transport, acute care and EMS.  Among these populations, success rates and confidence levels in use of the bougie and intubation in general are very high.  The reported failure rate falls well within the generally accepted percentage of difficult airways and comes close to the minute number of airway cases that cannot be managed effectively without surgical intervention.  Preference for the malleable stylet over the bougie for a first attempt remains greater than 50% overall and in every single credential group. This suggests that most providers still consider the bougie a difficult airway or rescue airway tool and have not adopted it as a first pass device. This is further supported by the 3 to 1 preference for using the bougie with the two person “railroad” technique rather than preloaded, suggesting that bougie is employed only after a difficult view is encountered. 

Part II of the Bougie review will examine the evidence of airway success rates when using the bougie and present the cases for and against using the bougie as a first attempt adjunct on every intubation attempt.

Thanks again for reading. Feel free to comment here or on Twitter @Crit_Care_Excel, and visit the website, www.critical-care-excellence.pro.

References
1.       Garza AG, Gratton MC, Coontz D, Noble E, Ma OJ. Effect of paramedic experience on orotracheal intubation success rates. J Emerg Med. 2003;25(3):251-6.
2.       Law JA, Broemling N, Cooper RM, et al. The difficult airway with recommendations for management--part 1--difficult tracheal intubation encountered in an unconscious/induced patient. Can J Anaesth. 2013;60(11):1089-118.
3.       TNATC Provider Manual 5th Ed ASTNA 2010

4.       Gataure PS, Vaughan RS, Latto IP. Simulated difficult intubation. Comparison of the gum elastic bougie and the stylet. Anaesthesia 1996; 51: 935-8.

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